Bernie Sanders rally in Waterloo, Iowa

Facebook is tracking the most-discussed candidates in Iowa today by users on its site.  Bernie Sanders is leading the pack with 42-percent of users posting about the Vermont senator.  Donald Trump is a distant second with just over 21-percent.  Hillary Clinton is third with 13-percent, Ted Cruz fourth with 10-percent and Rand Paul rounds out the top five with just over four-percent. 


Photo: Getty Images